1. Field of the Invention
The present invention is related to a locking device for an extension pipe of vacuum cleaner.
2. Description of the Related Art
In general, a vacuum cleaner is, as shown in FIG. 1, is comprised of a main body 10 usually having main parts such as a vacuum generating device therein, an operation handle 12 having a flexible hose 11 to be connected to the main body 10, an extension pipe 13 to be connected to the operation handle 12, a suction brush 14 to be connected to an end of the extension pipe 13, and a locking device for an extension pipe 15 for movably supporting the operation handle 12 and the extension pipe 13.
As shown in FIG. 1, the locking device 15 comprises a suction brush 14 and assorted assistant brushes (not shown), for example, for cleaning of narrow spaces. The locking device 15 is able to secure and release the connection between the operation handle 12 and the extension pipe 13.
FIG. 2 is a sectional view of a conventional locking device for an extension pipe. As shown in FIG. 2, a conventional locking device for an extension pipe comprises a holder 30 being coupled with an operation handle 12 and a locking/unlocking lever 40 for securing and releasing the connection between the holder 30 of the operation handle 12.
The holder 30 is in shape of a hollow pipe, comprising a locking hole 31 corresponding to the fixing hole 12a of the operation handle 12, and a supporting portion 32 protruding at a predetermined distance from the locking hole 31. To the opposite end of the operation handle 12 of the holder 30, the extension pipe 13 is connected, as shown in FIG. 1.
The locking/unlocking lever 40 includes a button portion 42 which is integrally formed on one end of a lever body 41 enclosing the holder 30, and at a predetermined space between the button portion 42 and the holder 30. Further, inside the other end of the lever body 41 is formed a hook portion 43 movable in and out through the locking hole 31 of the holder 30. A projection 44 is formed being supported by the supporting portion 32, between the hook portion 43 and the button portion 42.
In a conventional locking device for an extension pipe constructed as above, the locking/unlocking lever 40 turns up and down like a seesaw on the projection 44, accordingly the hook portion 43 of the holder 30 secures and releases the holder 30 with respect to the operation handle 12, moving in and out through the locking hole 31 of the holder 30.
Initially, that is, before an external force is applied to the button portion 42, the locking/unlocking lever 40 is in a status that the hook portion 43 is inserted in the locking hole 31 of the holder 30, as shown in FIG. 2, due to its recovery force of the lever body 41. Here, the hook portion 43 is also inserted into the fixing hole 12a of the operation handle 12 through the locking hole 31, and thus the holder 30 is secured in place.
On the other hand, when a pressing external force is applied to the button portion 42, the locking/unlocking lever 40 moves clockwise in FIG. 2 about the projection 44. Thus, the hook portion 43 becomes unlocked from the locking hole 31. At this time, the holder 30 can be separated from the operation handle 12 by drawing the holder 30 in a direction A in FIG. 2.
If an external force is removed from the button portion 42 after separating the holder 30, the locking/unlocking lever 40 now moves counterclockwise about the projection 44 of the lever body 41 due to its recovery force, so that the lever body 41 is returned to the initial position.
Further, if the holder 30 is again fit in with the operation handle 12 in a direction B in FIG. 2, the hook portion 43 is temporarily out of the locking hole 31, and is inserted into the fixing hole 12a of the operation handle 12 through the locking hole 31 when the locking hole 31 and the fixing hole 12a meet as the holder is sliding. Therefore, the holder 30 is secured in place.
However, in the above conventional locking device of a vacuum cleaner, because the projection 44 is placed between the button portion 42 and the hook portion 43, and especially because the button portion 42 of the locking/unlocking lever 40 is positioned opposite to the holder separating direction (direction A in FIG. 2), much force is required to press the button portion 42, and further, it becomes relatively harder to separate the holder 30.
Another problem of a conventional locking device 15 is that the locking/unlocking lever 40 needs to be large enough for the lever system in which the locking/unlocking lever 40 turns on the projection 44 upward and downward in a seesaw-like motion to lock or unlock the holder 30, so that it cannot be made compact.